Mining operations require blasting events that employ a plurality of detonators, each associated with an explosive charge. Often, the explosive charges are positioned within boreholes drilled into the rock to be blasted, and electric or electronic detonators are placed in association with the explosive charges, such that actuation of each detonator causes initiation of its associated explosive charge.
The electric or electronic detonators are remotely controlled via one or more associated blasting machines, of any type that is known in the art. Each blasting machine transmits command signals to each detonator such as ARM, DISARM, FIRE signals as well as other signals to program electronic detonators with information relevant to the blast such as detonator delay times. Traditionally, such command signals are transmitted from a blasting machine along wires that provide electrical connection from the blasting machine to each detonator. Traditionally, two type of wires are present at the blast site: (1) a trunk line (also known as a bus-wire or harness wire), which extends from the blasting machine to the general locality of the detonators; and (2) branch lines (also known as leg wires if they extend directly from a detonator), which provide electrical contact from the detonators to the trunk line.
Typically, branch lines are more robust than trunk lines, and often have larger diameters, because they are required to extend through a borehole to provide the required contact between the detonator and the trunk line. During setup of the blast apparatus, each detonator is placed in a borehole in association with an explosive charge, with the branch line (i.e. leg-wire extending from the detonator) extending up and out of the borehole. Conditions within the borehole, and various forces applied to the branch line, may cause abrasion and/or tugging on the branch line. For example, during stemming material such as gravel is added either to fill the borehole, or to provide spatial separation between decks of explosive charges and detonators. Thus, a borehole may include several detonators, each with a leg wire extending through and out of the borehole. Once the first (often the deepest) explosive charge and detonator has been positioned in the borehole, stemming material may be poured or shoveled into the borehole either manually or by machine, about the leg wire extending from the first detonator, before a second explosive charge and detonator are added to the borehole. A skilled artisan will therefore appreciate the need for robust leg-wires to prevent damage or breakage of the legwires, and to maintain electrical contact between the detonator and the harness wire.
Various connectors are known in the art to provide connection between branch line extending from a detonator, and a harness wire. Such connectors are sometimes known as insulation displacement connectors (IDCs) because they are required to displace insulating material that sheaths the electrically conductive material of the wire, in order to provide electrical contact between the wires. Typically, such connectors include some form of electrical terminal or bridge so that at least two wires (e.g. a trunk line and a branch line) may be held in close proximity and in electrical contact with the electrical terminal or bridge. Examples of such connectors are provided by U.S. Pat. No. 6,299,472 issued Oct. 9, 2001, and U.S. Pat. No. 6,442,755 issued Sep. 3, 2002, both of which are incorporated herein by reference.
Whilst the connectors of the prior art provide useful connectivity between trunk lines and branch lines, there use is somewhat limited to specific types of lines. There is a need in the art for connectors that are more versatile in terms of their ability to connect various types of wires at the blast site. There is also a need in the art for alternative methods for providing electrical connection between various components of a blast apparatus.